MATERIALS AND METHODS
4.4 Effect of contact time on metal ion concentration remaining in aqueous phase under uncontrolled and controlled pH conditions from mono-, binary- and
ternary-metal ion systems comprising of Cu(II), Pb(II) and Cr(III) ions
The effect of contact time on the metal ion concentration remaining in aqueous phase from different combinations of mono-, binary- and ternary-metal ion systems comprising of Cu(II), Pb(II) and Cr(III) have been investigated under uncontrolled and controlled pH conditions. The stock solutions of mono-metal ions were used to prepare solution of selected combinations of mono-, binary- and ternary-metal ion systems as indicated in Table 4.8. The required amounts (in terms of volume) of stock solutions of mono-metal ions were taken in a 1000 mL capacity glass beaker and added with sufficient amount of de-mineralized water to ensure that pH electrode is safely dipped into the liquid leaving sufficient space below for smooth operation of magnetic stirring bar without touching the lower tip of pH electrode. For experiments carried out under uncontrolled pH conditions, pH of the solution was initially adjusted to a value of 5.00 by adding required amounts (in terms of volume) of either acid (1N, 0.1N, 0.01N HCl) or base (1N, 0.1N, 0.01N NaOH). After adjusting the solution pH to 5.00, the content was transferred in to a 1000 mL capacity volumetric flask, added with de-
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Table 4.7: Input parameters for mono-, binary- and ternary-metal ion combinations for metal ion availability in aqueous phase under uncontrolled and controlled pH conditions with variation in solution pH using MINEQL+ software.
Combinations Input parameters with initial concentration (in mol/L)
Uncontrolled pH conditions Controlled pH conditions
M[Cu(0.60)] Cu(II) = 0.0013, SO4-2 = 0.0003 Cu(II) = 0.0012, CH3COO- = 0.0800, Na+ = 0.0560, SO4-2 = 0.0003 M[Pb(0.60)] Pb(II) = 0.0012, NO3- = 0.0006 Pb(II) = 0.0012, CH3COO- = 0.0800, Na+ = 0.0560, NO3- = 0.0006 M[Cr(0.60)] Cr(III) = 0.0018, NO3- = 0.0006 Cr(III) = 0.0012, CH3COO- = 0.0800, Na+ = 0.0560, NO3- = 0.0006 B[Cu(0.45)+Pb(0.15)] Cu(II) = 0.0009, SO4-2 = 0.0002,
Pb(II) = 0.0003, NO3- = 0.0002
Cu(II) = 0.0009, SO4-2 = 0.0002, Pb(II) = 0.0003, NO3- = 0.0002, CH3COO- = 0.0800, Na+ = 0.0560
B[Cu(0.30)+Pb(0.30)] Cu(II) = 0.0006, SO4-2 = 0.0002,
Pb(II) = 0.0006, NO3- = 0.0003 Cu(II) = 0.0006, SO4-2 = 0.0002, Pb(II) = 0.0006, NO3- = 0.0003, CH3COO- = 0.0800, Na+ = 0.0560
B[Cu(0.15)+Pb(0.45)] Cu(II) = 0.0003, SO4-2 = 0.0000,
Pb(II) = 0.0009, NO3- = 0.0005 Cu(II) = 0.0003, SO4-2 = 0.0000, Pb(II) = 0.0009, NO3- = 0.0005, CH3COO- = 0.0800, Na+ = 0.0560
B[Cu(0.60)+Pb(0.60)] Cu(II) = 0.0012, SO4-2 = 0.0003,
Pb(II) = 0.0012, NO3- = 0.0006 Cu(II) = 0.0012, SO4-2 = 0.0003, Pb(II) = 0.0012, NO3- = 0.0006, CH3COO- = 0.0800, Na+ = 0.0560
B[Cr(0.45)+Pb(0.15)] Cr(III) = 0.0014, Pb(II) = 0.0003, NO3- = 0.0006 Cr(III) = 0.0014, Pb(II) = 0.0003, NO3- = 0.0006, CH3COO- = 0.0800, Na+ = 0.0560
B[Cr(0.30)+Pb(0.30)] Cr(III) = 0.0009, Pb(II) = 0.0006, NO3- = 0.0006 Cr(III) = 0.0009, Pb(II) = 0.0006, NO3- = 0.0006, CH3COO- = 0.0800, Na+ = 0.0560
B[Cr(0.15)+Pb(0.45)] Cr(III) = 0.0005, Pb(II) = 0.0009, NO3- = 0.0006 Cr(III) = 0.0005, Pb(II) = 0.0009, NO3- = 0.0006, CH3COO- = 0.0800, Na+ = 0.0560
B[Cr(0.60)+Pb(0.60)] Cr(III) = 0.0019, Pb(II) = 0.0011, NO3- = 0.0012 Cr(III) = 0.0019, Pb(II) = 0.0011, NO3- = 0.0012, CH3COO- = 0.0800, Na+ = 0.0560
B[Cu(0.45)+Cr(0.15)] Cu(II) = 0.0009, SO4-2 = 0.0002,
Cr(III) = 0.0004, NO3- = 0.0001 Cu(II) = 0.0009, SO4-2 = 0.0002, Cr(III) = 0.0004, NO3- = 0.0001, CH3COO- = 0.0800, Na+ = 0.0560
B[Cu(0.30)+Cr(0.30)] Cu(II) = 0.0006, SO4-2 = 0.0002,
Cr(III) = 0.0010, NO3- = 0.0003 Cu(II) = 0.0006, SO4-2 = 0.0002, Cr(III) = 0.0010, NO3- = 0.0003, CH3COO- = 0.0800, Na+ = 0.0560
B[Cu(0.15)+Cr(0.45)] Cu(II) = 0.0003, SO4-2 = 0.0000,
Cr(III) = 0.0015, NO3- = 0.0004 Cu(II) = 0.0003, SO4-2 = 0.0000, Cr(III) = 0.0015, NO3- = 0.0004, CH3COO- = 0.0800, Na+ = 0.0560
B[Cu(0.60)+Cr(0.60)] Cu(II) = 0.0012, SO4-2 = 0.0003,
Cr(III) = 0.0020, NO3- = 0.0006 Cu(II) = 0.0012, SO4-2 = 0.0003, Cr(III) = 0.0020, NO3- = 0.0006, CH3COO- = 0.0800, Na+ = 0.0560
T[Cu(0.20)+Pb(0.20)+Cr(0.20)] Cu(II) = 0.0004, SO4-2 = 0.0000, Pb(II) = 0.0004, Cr(III) = 0.0007, NO3-= 0.0004
Cu(II) = 0.0004, SO4-2 = 0.0000, Pb(II) = 0.0004, Cr(III) = 0.0007, NO3- = 0.0004, CH3COO-= 0.0800, Na+= 0.0560
T[Cu(0.60)+Pb(0.60)+Cr(0.60)] Cu(II) = 0.0012, SO4-2 = 0.0003, Pb(II) = 0.0012,
Cr(III) = 0.0019, NO3- = 0.0012 Cu(II) = 0.0012, SO4-2 = 0.0003, Pb(II) = 0.0012, Cr(III) = 0.0019, NO3- = 0.0012, CH3COO- = 0.0800, Na+ = 0.0560
M[Cu(0.60)]
19.06 mL of Cu(II) SS added with acid or base to adjust initial pH 5.00 and final volume made to 1000 mL using DMW
19.06 mL of Cu(II) SS buffered to pH 5.00 with 80 mL of acetate buffer and final volume made to 1000 mL using DMW
M[Pb(0.60)]
62.16 mL of Pb(II) SS added with acid or base to adjust initial pH 5.00 and final volume made to 1000 mL using DMW
62.16 mL of Pb(II) SS buffered to pH 5.00 with 80 mL of acetate buffer and final volume made to 500 mL using DMW
M[Cr(0.60)]
10.40 mL of Cr(III) SS added with acid or base to adjust initial pH 5.00 and final volume made to 1000 mL using DMW
10.40 mL of Cr(III) SS buffered to pH 5.00 with 80 mL of acetate buffer and final volume made to 1000 mL using DMW
B[Cu(0.45)+Pb(0.15)]
14.30 mL of Cu(II) SS & 15.54 mL of Pb(II) SS added with acid or base to adjust initial pH 5.00 and final volume made to 1000 mL using DMW
14.30 mL of Cu(II) SS & 15.54 mL of Pb(II) SS buffered to pH 5.00 with 80 mL of acetate buffer and final volume made to 1000 mL using DMW
B[Cu(0.30)+Pb(0.30)]
9.53 mL of Cu(II) SS & 31.08 mL of Pb(II) SS added with acid or base to adjust initial pH 5.00 and final volume made to 1000 mL using DMW
9.53 mL of Cu(II) SS & 31.08 mL of Pb(II) SS buffered to pH 5.00 with 80 mL of acetate buffer and final volume made to 1000 mL using DMW
B[Cu(0.15)+Pb(0.45)]
4.78 mL of Cu(II) SS & 46.62 mL of Pb(II) SS added with acid or base to adjust initial pH 5.00 and final volume made to 1000 mL using DMW
4.78 mL of Cu(II) SS & 46.62 mL of Pb(II) SS buffered to pH 5.00 with 80 mL of acetate buffer and final volume made to 1000 mL using DMW
B[Cu(0.60)+Pb(0.60)] 19.06 mL of Cu(II) SS & 62.16 mL of Pb(II) SS added with acid or base to adjust initial pH 5.00 and final volume made to 1000 mL using DMW
19.06 mL of Cu(II) SS & 62.16 mL of Pb(II) SS buffered to pH 5.00 with 80 mL of acetate buffer and final volume made to 1000 mL using DMW
B[Cr(0.45)+Pb(0.15)]
7.80 mL of Cr(III) SS & 15.54 mL of Pb(II) SS added with acid or base to adjust initial pH 5.00 and final volume made to 1000 mL using DMW
7.80 mL of Cr(III) SS & 15.54 mL of Pb(II) SS buffered to pH 5.00 with 80 mL of acetate buffer and final volume made to 1000 mL using DMW
B[Cr(0.30)+Pb(0.30)]
5.20 mL of Cr(III) SS & 31.08 mL of Pb(II) SS added with acid or base to adjust initial pH 5.00 and final volume made to 1000 mL using DMW
5.20 mL of Cr(III) SS & 31.08 mL of Pb(II) SS buffered to pH 5.00 with 80 mL of acetate buffer and final volume made to 1000 mL using DMW
Table continued on next page…..
57 Table 4.8 continues……
B[Cr(0.15)+Pb(0.45)]
2.60 mL of Cr(III) SS & 46.62 mL of Pb(II) SS added with acid or base to adjust initial pH 5.00 and final volume made to 1000 mL using DMW
2.60 mL of Cr(III) SS & 46.62 mL of Pb(II) SS buffered to pH 5.00 with 80 mL of acetate buffer and final volume made to 1000 mL using DMW
B[Cr(0.60)+Pb(0.60)]
10.40 mL of Cr(III) SS & 62.16 mL of Pb(II) SS added with acid or base to adjust initial pH 5.00 and final volume made to 1000 mL using DMW
10.40 mL of Cr(III) SS & 62.16 mL of Pb(II) SS buffered to pH 5.00 with 80 mL of acetate buffer and final volume made to 1000 mL using DMW
B[Cu(0.45)+Cr(0.15)]
14.30 mL of Cu(II) SS & 2.60 mL of Cr(III) SS added with acid or base to adjust initial pH 5.00 and final volume made to 1000 mL using DMW
14.30 mL of Cu(II) SS & 2.60 mL of Cr(III) SS buffered to pH 5.00 with 80 mL of acetate buffer and final volume made to 1000 mL using DMW
B[Cu(0.30)+Cr(0.30)] 9.53 mL of Cu(II) SS & 5.20 mL of Cr(III) SS added with acid or base to adjust initial pH 5.00 and final volume made to 1000 mL using DMW
9.53 mL of Cu(II) SS & 5.20 mL of Cr(III) SS buffered to pH 5.00 with 80 mL of acetate buffer and final volume made to 1000 mL using DMW
B[Cu(0.15)+Cr(0.45)]
4.78 mL of Cu(II) SS & 7.80 mL of Cr(III) SS added with acid or base to adjust initial pH 5.00 and final volume made to 1000 mL using DMW
4.78 mL of Cu(II) SS & 7.80 mL of Cr(III) SS buffered to pH 5.00 with 80 mL of acetate buffer and final volume made to 1000 mL using DMW
B[Cu(0.60)+Cr(0.60)]
19.06 mL of Cu(II) SS & 10.40 mL of Cr(III) SS added with acid or base to adjust initial pH 5.00 and final volume made to 1000 mL using DMW
19.06 mL of Cu(II) SS & 10.40 mL of Cr(III) SS buffered to pH 5.00 with 80 mL of acetate buffer and final volume made to 500 mL using DMW
T[Cu(0.20)+Pb(0.20)+Cr(0.20)]
6.35 mL of Cu(II) SS, 20.72 mL of Pb(II) & 3.47 mL of Cr(III) SS added with acid or base to adjust initial pH 5.00 and final volume made to 1000 mL using DMW
6.35 mL of Cu(II) SS, 20.72 mL of Pb(II) & 3.47 mL of Cr(III) SS buffered to pH 5.00 with 80 mL of acetate buffer and final volume made to 1000 mL using DMW T[Cu(0.60)+Pb(0.60)+Cr(0.60)] 19.06 mL of Cu(II) SS, 62.16 mL of Pb(II) & 10.40 mL of
Cr(III) SS added with acid or base to adjust initial pH 5.00 and final volume made to 1000 mL using DMW
19.06 mL of Cu(II) SS, 62.16 mL of Pb(II) & 10.40 mL of Cr(III) SS buffered to pH 5.00 with 80 mL of acetate buffer and final volume made to 1000 mL using DMW SS = Working solution, DMW = De-mineralized water, acid or base (1N, 0.1N, 0.01N) added to adjust initial pH level under uncontrolled pH conditions.
(which worked out to be 8 mL of buffer solution in 50 mL of solution volume). After buffering the solution pH to 5.00, the content was transferred in to a 1000 mL capacity volumetric flask, added with de-mineralized water up to the mark and mixed thoroughly again. These solutions (one prepared for uncontrolled pH conditions experiments while another one prepared for controlled pH conditions experiments) were termed as experimental solution. 50 mL each of the experimental solution was transferred to 9 specimen tubes of 100 mL capacity. Each of the specimen tubes was further added with a fixed dose of 0.6 g GAA (which worked out to be 12 g GAA/L). The capped specimen tubes containing the mixture (i.e. metal ion solution with initial pH adjusted or buffered and GAA) were mounted on an end-over-end rotary shaker (Model: Reico, M/S REICO Equipment & Instrument Pvt. Ltd., Kolkata, India) and mixed at a constant speed of 66 revolutions per minute (rpm) at room temperature (30±1 oC). The specimen tubes were taken out from the shaker one by one at predetermined time intervals. The liquid phase was separated from the solid phase by using an ordinary filter paper (Make: O Sicerin and Biva, Kolkata, India). The final solution pH and the residual metal ion concentration in the separated liquid phase were estimated. All the experiments were conducted in triplicate and average values were used for analysis of the results.
4.5 Kinetics of metal removal under uncontrolled pH conditions and metal uptake